On Faraway Shoals, Researchers Struggle to Save the Seals

By JOE SPRING

Published: October 31, 2006

In a small white cinder block room here in the French Frigate Shoals, five monk-seal biologists crowded around a dead Hawaiian monk seal laid out on a table covered with white plastic.

The pup's black eyes reflected the light and its whiskers quivered at a touch, but a shark had bitten off its hind flippers. A large gash and 14 smaller cuts pockmarked its back. When the scientists had finished doing the animal equivalent of an autopsy, had taken samples for testing and removed the seal, Suzanne Canja, a field biologist, took a moment to contemplate the empty table.

''Another poor little guy,'' she said. ''It's really sad.''

The Hawaiian monk seal is having a bad year. In 2006, the seals set a record for the lowest number of pups born since monitoring began in 1983. On French Frigate Shoals, almost 600 miles northwest of Honolulu, where the species' largest subpopulation lives, almost a quarter of the pups died or disappeared, perhaps lost to predation by sharks.

The outlook for juveniles past the pup stage is not any better. Young seals throughout the Northwestern Hawaiian Islands archipelago are starving, and scientists have not been able to figure out why.

This is not the first difficult year for the seal, which has declined an estimated 60 percent since the late 1950s to a population of approximately 1,200.

Bud Antonelis, head of the monk seal protected species division of the National Marine Fisheries Service, said the species ''is now in a crisis situation.''

''The population may fall below 1,000 in the next five years,'' Dr. Antonelis said.

Adults have a tan to pewter-colored coat, and may grow up to eight feet in length and weigh more than 600 pounds. When provoked, monk seals have been known to sink their canines into sharks, biting through the skin.

Their defenses haven't been much good against people, however.

In the 19th century, guano miners, whalers, and sealers traveled the Northwestern Hawaiian Islands -- a largely uninhabited chain that extends for some 1,200 miles and includes the island of Midway -- killing the seals for their meat, blubber, and hides.

During and after World War II, military personnel and their dogs assigned to patrol the islands harassed the seals into giving up large beaches protected by shallow reefs, forcing them onto smaller beaches where the pups were unprotected from shark predation and heavy surf.

In 1976, the federal government made it illegal to harass, disturb or take the seal under the Endangered Species Act and the Marine Mammal Protection Act.

American military pullbacks left remote field stations in the islands abandoned.

This year, President Bush declared the 140,000-square-acre area around the northwestern Hawaiian Islands a national monument. Under the measures set forth by the president, fishing is prohibited in the monument for five years.

To limit their effect on the seals, the field biologists stationed on French Frigate Shoals survey small islands the size of tennis courts from boats.

On larger islands, the size of football fields, the biologists are so wary of disturbing the seals that they crawl on the sand and duck into two-foot-deep pits dug by nesting turtles.

Still, humanity's impact is unavoidable. Trash washes up daily on the reefs and islands of the archipelago, and seals can become entangled in some of the waste and drown or starve.

Rising sea levels threaten to inundate many of the preferred beaches on islands typically only six to eight feet high.

The small number of seals in the main Hawaiian Islands are susceptible to diseases like canine distemper, leptospirosis and toxoplasma introduced by dogs, cats and livestock.

''If the seals were to contact the disease here and travel up to the other islands and spread it there, that would be a problem,'' said Jason D. Baker, a monk-seal biologist with the National Marine Fisheries Service.

The main threat to the seals, scientists say, is juvenile survivorship. Across the archipelago, young seals are in trouble, but the longest and most severe decline has occurred at French Frigate Shoals. From 1989 to 2005, the population fell by more than 70 percent, according to beach counts of the seals.

In a healthy population, the age structure looks something like a pyramid, with more young individuals than adults.

At French Frigate Shoals, that structure is inverted. More adults exist than juveniles. As those adults die off, fewer juveniles grow up to replace them. The major cause of death for the young seals is their unexplained starvation.

Possible explanations include changes in prey distribution and abundance, a depleted lobster population that has not recovered despite being closed since 2000, and competition for food from other top predators like sharks and jacks.

Scientists have only recently begun detailed studies of the seals' foraging range and diet. Ten years ago, researchers thought the seal fed on fish in shallow reefs near its resting beach.

Satellite tags, scat analysis, and footage from a National Geographic ''crittercam'' mounted on the seals themselves helped scientists realize that the animals may travel farther than 100 miles, to depths greater than 1,500 feet, and to sand beds and submerged pinnacles to dine on prey that includes fish, octopus, and crustaceans.

While scientists try to understand the cause of starvation in juveniles, they are trying to prevent losses from the problems they do understand.

On French Frigate Shoals, they cull Galapagos sharks that prey upon monk seal pups. Scientists and volunteers, conducting annual cleanups, have collected more than 494 tons of debris since 1996. Scientists have now moved the malnourished pups to Midway as part of a captive feeding plan. And they mull over the possibility of restoring beaches on French Frigate Shoals to mitigate habitat that may be lost to rising sea levels.

After so many years when human interaction with the seal meant decline, scientists hope now that measured interaction can stem the decline and spur recovery.

''I think that various human impacts have stacked the cards against the species, and it is our job to try and counter that in any way that we can,'' Dr. Baker said.

Photos: ENDANGERED -- Entangling marine debris accounts in part for Hawaiian monk seals' decline, which has been severe at French Frigate Shoals, top. This year, it has lost almost a quarter of its population of pups. (PhotoS by National Oceanic and Atmospheric Administration [NOAA]; top, Joe Spring/NOAA)

Correction: November 3, 2006, Friday
Because of an editing error, an article in Science Times on Tuesday about an effort to save Hawaiian monk seals misstated the terms of a federal ban on fishing in the Northwestern Hawaiian Islands Marine National Monument, where the species' largest subpopulation lives. In establishing the monument last June, President Bush said commercial fishing would be phased out over five years; he did not prohibit fishing there for the next five years.